The Redox Process of Zn2+/Zn on Au/Ionic Liquid Interface Studied by In-Situ Surface-Enhanced Infrared Absorption Spectroscopy

Abstract

In-situ surface-enhanced infrared absorption spectroscopy (SEIRAS) is employed to investigate the redox process of Zn2+/Zn on Au electrode surface in ionic liquid (IL) system containing [Bmim]BF4 (1-butyl-3-methylimidazolium tetrafluoroborate) mixed with zinc tetrafluoroborate (Zn(BF4)2), within the potential range of 0.2 V~ -2.6 V. The interface structure as well as the rearrangement of the ions during the zinc electrodeposition process has been traced and explained in details. The results suggest that [Bmim]+ cations integrates with anions to form high-order ions with positive charge in pure [Bmim]BF4 . The high-order ions will be broken by Zn2+ absorbed at the interface during zinc reduction, which leads to the reorientation of the [Bmim]+ cations from a vertical configuration to a more parallel one at negative potential. Meanwhile, the [Bmim]+ cations are gradually desorbed from the interface during the zinc electrodeposition process. The feature of the anions behavior is also discussed.